No outgoing audio after returning from hold & transfer drops call [sometimes]

We are using FreePBX, and have PolyCom SoundPoint IP 321 phones running the latest firmware.

Our former Philippines tech migrated our PBX to a more powerful Amazon instance last Monday, and we have had issues transferring and holding calls since then. He has since left the company due to a severe health problem and is not reachable at this time.

Sometimes, with no discernible pattern, after returning a call from hold or receiving a transferred call, the caller does not hear our microphone but we hear them.

A second issue we are facing is that when a caller is transferred, sometimes the caller is dropped altogether and has to call us back.

Now, the weird thing is that this is only happening in one of our three locations. Our Atlantic office has the same phones with no problems, and our overseas office has different phones with no problems. I thought it was our phones but I have not been able to resolve it with any amount of configuration or reviewing of log files. Despite the localization of the problem, somebody with more experience offered the comment ‘it sounds like a PBX problem’.

Can somebody here please weigh in? We are in the telecom industry and this has a severe effect on our image with customers.


Bump…need help!

Same issue as ours also. Need help!

A couple of ideas you may want to try:

  • Make sure you have any type of SIP ALG (or SIP proxy, VoIP helper, etc.) disabled in your firewall/router. Those tend to break more than they fix. (Although, if it was previously working, then this shouldn't be the issue.)
  • Amazon instances generally sit behind NAT. When changing the instance, it may have been assigned a new internal or external IP (depending on how you have your Amazon instances configured.) In FreePBX, look under Settings, then Asterisk SIP Settings. Make sure it's set to static IP, then hit the Auto Configure button. That tends to get the right settings in there for the FreePBX instances we use on EC2. (Note, usually if this isn't set correctly, you end up with no audio on calls, at least in our experience. But it's worth checking.)
  • If your instance's public IP changed, and you had any rules in your firewall related to traffic to/from your instance, make sure you've updated those rules with the new IP address! It may have been that the previous guy had to do some tweaking of the firewall to make it work correctly, and if the IP's changed, those tweaks may need to be updated.

That’s all I can think of at the moment. Maybe someone else will have more ideas.

One other note… (that’s what I get for posting while multi-tasking and not comprehending the entire thing!)

If the different locations all connect to the same FreePBX instance at Amazon, then I’d think it’s more likely to be a configuration issue with the one location (i.e. firewall rules that need updating to a new IP.) Stuff on the FreePBX server should affect all locations. So, I’d check the firewall stuff first, then start looking at FreePBX. It’s possible those IP settings in FreePBX are wrong, and it’s just only affecting one location due to different phones/firewall/etc. being at other locations.


We used an elastic IP and assigned the same IP to the new instance
SIP ALG and NAT rules stayed the same; disabled where appropriate
We switched back to the old instance and the problem was alleviated

Dom, we work together :smiley: Though, I suppose not many of the team knows my gaming handle yet…I should get a LoL team together :slight_smile:

We’re going to be going hard at this to see what the differences are in our two instances; any config differences, firewall settings, etc. We already know it’s a different CentOS distro.

Will post back if we find out what it was or need more help